1. Field of the Invention
The present invention relates generally to radio frequency identification (RFID) tags, or cards, and pertains, more specifically, to the manufacture of RFID tags and intermediate products employed in manufacturing processes for such tags.
RFID tags are finding increased and widespread use as more systems are developed and placed into service for managing the inventory and sale of a wider variety of goods. These RFID tags are applied to the goods and employ electronic circuitry responsive to radio frequency (RF) signals for providing readily monitored identification data pertaining to the goods. By virtue of the manner in which RFID tags are attached to and carried by various articles, the tags must be made compact, usually are thin and flexible, and should be inexpensive enough to be readily expendable.
2. Description of Related Art
The circuitry of an RFID tag includes an antenna connected to other circuit components of the tag. The antenna typically occupies a substantial portion of the area dimensions of the tag and usually is constructed of a relatively thin copper foil for flexibility and for maximum effectiveness in responding to RF signals. Current manufacturing processes are similar to those employed in the manufacture of printed circuit boards. A thin copper foil, typically 0.0005 to 0.0015 inch in thickness, is laminated to a flexible synthetic polymeric substrate, such as a PET (polyethylene terephthalate) substrate having a thickness of about two to five mils. The desired antenna configuration then is photochemically etched from the laminate, that is, copper is chemically milled away leaving the desired copper pattern laminated to the chemically inert substrate. The substantial cost of the copper/PET laminate coupled with the relatively high cost of processing the substrate by chemical etching results in a total cost which becomes excessive when viewed in the light of the increasing demand for inexpensive, readily expendable RFID tags.